Surface cleaning
A simple way to clean off a surface covered in acrylic paint bits is to cover that surface in a thin layer of gel medium (or acrylic paint), lay paper over it, press the paper down in the same manner you'd do if doing a hand print, and leave the paper there until everything is dry.
Pull up.
Voila. Clean, or mostly so, surface.
You may need to repeat this process more than once. This also works for cleaning gel plates (commercial, et al).
The upshot is that you now have a metric fucktonne of collage paper or substrates for future artworks.